> Then I pushed the bar away from me as hard as I could. The indicator
> measured .007 of movement. The same thing happens when I pull the
> steel bar toward me.
Which implies to me that you have four*** thousanths of clearance in
the bearings, which is a lot.
First you have to re-do the measurement, because you have done it
a bit incorrectly. Not a lot wrong, but it is important to do this
right as it can save you a lot of time later on.
Remove the CRS you have in the chuck. Remove the chuck from the
spindle. Remove any backplates or whatnot from the spindle nose as
well, so you are looking right at the the threaded portion of the
spindle as it emerges from the headstock. Now put your indicator
directly on the unthreaded part of the spindle (the register diameter)
as it emerges from the headstock, as close to the headstock casting
as possible consistent with getting the indicator to function properly.
Have the indicator mounted so it measures the up/down play on the
spindle. Now push down on on a s***of rod, or a broomstick, or
whatever, that is in the spindle hole of the machine, and while
doing so, zero out the indicator. Now push up on the stick and
note the reading on the dial. This is the TIR that will have
to be removed by subtracting shims from under the cap.
The readings you took on the stock in the chuck are overestimating
the clearance, I think.
If this machine is like most SB lathes I know (with the exception of
the 9" ones) then there will be bolts that hold the bearing caps
down, and then there will be two pipe plugs between them on top of
the cap. If this is the case, DO NOT attempt to remove the bearing
caps before doing this first: remove the pipe plugs and under them
you will see screws (either slotted or allen head) which must be
These screws pull up on an expander wedge that is locked into the
bearing shell inside the cap. Attempting to remove the cap (by force)
without removing those screws will destroy the bearing pretty well.
Once the cap is off, look for the shims that have been mentioned.
There is a shim pack with two thou shims all soldered together which
will total something like 20 thou in a new machine, and then a single
one thou shim that you can add or suptract to get the clearance just
right. Try to keep the front and rear shims the same thickness in
each of the headstock bearings. You should adjust both bearings in
this fashion, of course.
If the spindle clunks then things got pretty worn, and I hope you
have the shims to tighten it up. Why did it get so worn, was this
machine abused/neglected? Was it run without oil? There should be
two large oil cups and they should be full of oil when it is running.
There must be a wick under each bearing to supply oil to them, and
if they are missing or damaged then the machine will wear rapidly,
even if you snug it up again. Best is when the oil does drip a bit
from the bottom of the spindle nose during operation, as then you
*know* the bearing is getting oil.
Good luck, please report back and let us know what you discover
upon further inspection.
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